1. Field of the Invention
This invention relates to connectors for electrical and microelectronic devices and, in particular, to an apparatus and method for extracting a cast column grid array and bonded substrate from the column grid array mold.
2. Description of Related Art
Cast column grid array (CCGA) connections are used in place of conventional solder balls to electrically connect microprocessors and other electronic components to supporting substrates. With the need for increasing cast column grid array densities, such as recent products having a pitch or column-to column spacing of one millimeter, the process of extracting the CGA substrates from the graphite casting mold becomes more difficult. Present methods for extracting the CCGA substrates from casting molds are labor-intensive, and subject the mold and CCGA product to damage.
Prior art methods specifically directed at CCGA extraction have been tried with only limited success. Using a clamp to pull or unplug the assembly often results in tensile failure of the soft cast pins, as well as imposing a requirement for relief features on the carrier side of the mold that weakens it. The employment of interstitial or edge bearing pins that bear on the carrier have also been tried with limited success due to the lack of clearance between pins and/or part damage from limited bearing surface. Implementation of close tolerance injection molding also eliminates the option of providing clearance holes for extraction within the area of the feature array, since all features in this area will be filled with solder or other casting material. If the extraction forces do not lift the array out in a perpendicular fashion, the cast pins tend to bind in the mold bores. The resulting jamming causes pin and mold damage as well as terminally jamming the cast array in the mold.
Extraction of molded structures by use of multiple ejector pins typically utilize a set of pins integral to the mold structure itself and do not address electronic assemblies. Prior patents such as U.S. Pat. No. 5,429,492 to Taniyama, U.S. Pat. No. 5,236,364 to Herbst, U.S. Pat. No. 4,009,979 to Martin, U.S. Pat. No. 3,899,282 to Jesse, and U.S. Pat. No. 4,661,055 to Prince disclose a variety of pin-type extraction schemes that do not address extraction of remotely filled molds/castings that have been subject to a secondary casting/attachment step.
Accordingly, there is a need for a process and apparatus which overcomes the aforementioned problems and extracts CCGA substrates from the casting mold with very little operator effort, and may further be utilized with automated tooling.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an improved process and apparatus for extracting from a casting mold.
It is another object of the present invention to provide a CCGA substrate extraction process and apparatus which is less labor-intensive.
A further object of the invention is to provide an extraction process and apparatus which is less susceptible to damaging the CCGA substrate and/or interconnect on the array.
It is yet another object of the present invention to provide a CCGA substrate extraction process and apparatus which may accommodate various grid arrays and can be automated.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.